(6aj) Development of Catalysts for Energy and Environmental Applications

Over the next 30 years, the global energy demand is expected to increase by 60% to maintain pace with current projections of population and economic growth.^[1]  Fossil fuels will continue to provide a significant fraction of the energy supply; however, cleaner technologies, including solar, wind and nuclear will become prominent industries to meet the required demand.  As the burning of fossil fuels continues into the foreseeable future, it is necessary to develop more efficient processes to decrease energy usage and the associated CO₂ emissions.  With the threat of climate change and ocean acidification becoming more apparent each year,^[2] efforts must be put forth to not only develop new forms of clean energy, but also capture and utilize CO₂ as a commodity.  These large-scale CO₂ conversion processes require the discovery of active and low-cost catalysts.

Development of catalysts for CO₂ conversion can be divided into three areas: synthesis, in-situ characterization, and discovery, with significant research opportunities available in each area.  In catalyst synthesis, the most promising methods include: atomic layer deposition, colloidal synthesis and incipient wetness impregnation.  Although innovative synthesis methods, such as core-shell nanoparticles, can be extremely effective, uniform bimetallic particles can be easily and uniformly synthesized via incipient wetness impregnation.  Characterization of catalysts by in-situ techniques is necessary to identify critical intermediates and understand the effect of reaction environments on catalyst structure.  A previous study on CO₂ conversion used in-situ X-ray absorption near edge spectroscopy (XANES) on Mo₂C to confirm the effect of the reaction environment on catalyst oxidation states.^[3]

Catalyst discovery is the most general area of catalyst development, but perhaps the most important.  Previous studies demonstrate that reducible oxide supports, such as CeO₂, exhibit high activity in CO₂ conversion experiments because of their ability to exchange oxygen with CO₂.^[4]  Molybdenum carbide (Mo₂C), a non-precious metal catalyst, also shows promise as an active and selective catalyst for CO₂ conversion.^[3]  These materials are strikingly different, but have a fundamental similarity, which is they are each able to uptake and exchange oxygen with CO₂.  Because of the importance of oxygen exchange in reactions with CO₂, oxygen binding energy could be a valuable descriptor when searching for CO₂ conversion catalysts.  The discovery of such descriptors is an extremely powerful tool that can be applied beyond CO₂ conversion and into other applications of environmental catalysis.

Teaching Interests:  Courses that I would be interested in teaching are kinetics and an introductory course in chemical engineering principles.  The introductory course could be basic heat and mass transfer or an overview of the state of the field.  A professor at Johns Hopkins once told me, “Everything is chemical engineering.  If you name an item in your life, I can tell you how chemical engineering is involved.”  I believe this principle should be imparted into young chemical engineers as early as possible.  The classic view of chemical engineers as designing large reactors and processes is still relevant, but preparing students for current challenges in energy and climate change is also important.  Broadening students’ views of the field has the potential to attract bright minds that might not be set on chemical engineering.  I would also like to design an elective course that prepares students for solving problems in energy.  These problems naturally lend themselves to applications of thermodynamics, transport, and kinetics, while exposing students to the current state of the field.  This type of course and thought process clearly exemplifies my dual responsibility as an academic.